1. Field of the Invention
This invention relates to controlling a heating system. More particularly, this invention relates to ensuring that controller memory is properly programmed with safety critical information corresponding to a heating system.
2. Description of the Prior Art
Traditionally, heating systems such as burners, ovens and furnaces have used electromechanical limit switches to monitor safety-related parameters such as pressures and temperatures. When the safety-related parameters reached limits, which were set in the electromechanical limit switches, the electromechanical limit switches would automatically open or close to control the heating system. Heating system operators could exchange or replace controllers in the heating system without affecting the limits since they were set in the electromechanical limit switches.
However, many heating system controllers are now microcomputer-based heating system controllers that interface with solid-state analog sensors. The solidstate analog sensors provide the microcomputer-based controller with a continuous signal representing the safety-related parameters such as pressures and temperatures. The limits, which were previously set at the electromechanical limit switches, are stored in memory in the microcomputer-based controller where their values can be modified by the heating system operator. Therefore, when a heating system operator exchanges or replaces a microcomputer-based controller, it has a much greater effect on system operation and safety than before.
For this reason, the heating system operator must re-enter limit and timing values that are proper for the heating system which is receiving the new controller. Some operators may choose to ignore the task of reprogramming the new controller or they may forget or be unaware of the need for reprogramming. This could lead to improper and possibly hazardous control of the heating system by the new controller.